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Income Taxes - Additional Information (Details) $ in Thousands | 12 Months Ended
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Dec. 31, 2019 CNY (¥) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 CNY (¥) | Dec. 31, 2017 CNY (¥)
Income Taxes [Line Items] |  |  |  |
Statutory income tax rate | 25.00% | 25.00% | 25.00% | 25.00%
Income tax expenses | ¥ 2,440,000 | $ 350 | ¥ 0 | ¥ 0
Income tax expenses if the tax holidays granted to Beijing Sunlands were not available | 0 |  |  |
Uncertain tax positions | ¥ 0 |  | 0 | 0
Income tax rate outside the PRC | 25.00% | 25.00% |  |
Hong Kong |  |  |  |
Income Taxes [Line Items] |  |  |  |
Income tax expenses | ¥ 0 |  | 0 | 0
Hong Kong | For the First 2 Million Profits |  |  |  |
Income Taxes [Line Items] |  |  |  |
Statutory income tax rate | 8.25% | 8.25% |  |
Hong Kong | For the Remaining Profits |  |  |  |
Income Taxes [Line Items] |  |  |  |
Statutory income tax rate | 16.50% | 16.50% |  |
China |  |  |  |
Income Taxes [Line Items] |  |  |  |
Statutory income tax rate | 25.00% | 25.00% |  |
Deferred income tax expense | ¥ 2,440,000 |  | ¥ 0 | ¥ 0
China | subsidiaries and the Variable Interest Entities |  |  |  |
Income Taxes [Line Items] |  |  |  |
Statutory income tax rate | 25.00% | 25.00% |  |
Operating loss carryforwards | ¥ 2,923,067 |  |  |
Expiration start date | Dec. 31, 2020 | Dec. 31, 2020 |  |
Expiration end date | Dec. 31, 2029 | Dec. 31, 2029 |  |
China | 2016 | Beijing Sunlands |  |  |  |
Income Taxes [Line Items] |  |  |  |
Preferential tax rate description | Beijing Sunlands was qualified as “high and new technology enterprise strongly supported by the State” (“HNTE”) and was accordingly entitled to a preferential tax rate of 15% from calendar years 2016 through 2021 and is expected to be subject to an EIT rate of 15% as long as it maintains its status as a HNTE. | Beijing Sunlands was qualified as “high and new technology enterprise strongly supported by the State” (“HNTE”) and was accordingly entitled to a preferential tax rate of 15% from calendar years 2016 through 2021 and is expected to be subject to an EIT rate of 15% as long as it maintains its status as a HNTE. |  |
Preferential tax rate | 15.00% | 15.00% |  |
Preferential tax exemption approved start year | 2016 | 2016 |  |
Preferential tax exemption approved end year | 2021 | 2021 |  |

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